A medical elongated body including a catheter main body consisting of a hollow member in which a lumen is formed or a balloon catheter or the like including an inner tube shaft in which a guide wire lumen is formed may be used when performing various medical procedures in a biological organ of a living body. In general, the medical elongated body or inner tube shaft include an elongated tube body and a distal member disposed at a distal portion of the elongated tube body. In some cases, the distal member is formed of a material which is more flexible than the tube body material in order to prevent any damage to a biological lumen such as a blood vessel.
The tube body and the distal member are preferably joined to one another by fusing (i.e., a joining process such as welding or thermal bonding) so as to secure sufficient joining strength between the tube body and the distal member. However, in some cases, fusing properties between both of the tube body and the distal member deteriorate. The quality of the joint may deteriorate based on the material properties of the elements being joined, that is, the combination of a material for forming the tube body and a material for forming the distal member. In such a case, it is difficult to obtain sufficient joining strength (i.e., an adequate joint). As a result, the scope for selecting various materials constituting the tube body and the distal member becomes narrow.
International Patent Application Publication No. 2011/070844 discloses, for example, a method for stacking a part of a tube constituting an introduction destination area (corresponding to the distal member) on an inner peripheral surface side or an outer peripheral surface side of a tube body and fusing the tube body and the tube in the stacked state. According to this method, the joining strength between the tube body and the tube is improved in a portion in which the tube body and the tube are stacked. Therefore, it is considered that it is also possible to suppress the deterioration of the joining strength caused by the combination of the formation materials.